I had a very exciting experience! The speedboat, in particular, was incredibly fun and only cost about 1500 yen extra per person, so it's definitely a must-do if you take this tour! For kayaking, your lower body will get wet, so I recommend wearing a swimsuit or bringing a change of clothes. It was cloudy this time, but I'm sure it would be absolutely amazing if the weather were good! In early spring, the deck can be a bit chilly, so it's a good idea to bring a light jacket. Insect repellent is also recommended!